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To receive AM radio, you want an RLC circuit that can be made to resonate at any frequency between 500 and 1650 kHz. This is accomplished with a fixed 1.00 μH inductor connected to a variable capacitor. What range of capacitance is needed?

a. 1.25 - 4.11 μF
b. 5.00 - 10.0 μF
c. 0.625 - 2.05 μF
d. 2.50 - 8.22 μF

1 Answer

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Final answer:

The capacitance range needed for an RLC circuit to tune between 500 and 1650 kHz with a fixed inductor of 1.00 µH is approximately 0.625 to 2.05 µF, which corresponds to option c.

Step-by-step explanation:

To calculate the range of capacitance needed for an RLC circuit to resonate at frequencies between 500 and 1650 kHz with a fixed inductor of 1.00 µH, we use the resonance formula of an LC circuit:

f = \frac{1}{2\pi\sqrt{LC}}

Where:

  • f is the resonant frequency
  • L is the inductance
  • C is the capacitance

To find the capacitance range, we rearrange this equation to solve for C:

C = \frac{1}{(2\pi f)^2 L}

Calculating the capacitance for the lower frequency limit (500 kHz) and the higher frequency limit (1650 kHz), we get:

  • C for 500 kHz: C = \frac{1}{(2\pi 500 \times 10^3)^2 \times 1 \times 10^{-6}} Highly approximated to ≈ 2.05 µF
  • C for 1650 kHz: C = \frac{1}{(2\pi 1650 \times 10^3)^2 \times 1 \times 10^{-6}} Highly approximated to ≈ 0.625 µF

Thus, the required range of capacitance is from approximately 0.625 to 2.05 µF, making option c the correct option in the final answer.

User Danny Brady
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